261953302661 has 4 divisors (see below), whose sum is σ = 262898982732. Its totient is φ = 261007622592.

The previous prime is 261953302619. The next prime is 261953302669. The reversal of 261953302661 is 166203359162.

261953302661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 163564433761 + 98388868900 = 404431^2 + 313670^2 .

It is a cyclic number.

It is not a de Polignac number, because 261953302661 - 2¹⁰ = 261953301637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261953302669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 472839620 + ... + 472840173.

It is an arithmetic number, because the mean of its divisors is an integer number (65724745683).

Almost surely, 2^261953302661 is an apocalyptic number.

It is an amenable number.

261953302661 is a deficient number, since it is larger than the sum of its proper divisors (945680071).

261953302661 is an equidigital number, since it uses as much as digits as its factorization.

261953302661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 945680070.

The product of its (nonzero) digits is 349920, while the sum is 44.

The spelling of 261953302661 in words is "two hundred sixty-one billion, nine hundred fifty-three million, three hundred two thousand, six hundred sixty-one".